Timing and frequency synchronization among network entities that communicate with each other is an important issue in network performance. The accuracy of the synchronization between network nodes affects the performance of systems attached to the network and also the overall performance of the network. The IEEE 1588 protocol, referred to as the Precision Time Protocol (PTP), is a technique for providing robust cost-effective time synchronization for distributed systems.
Conventional IEEE 1588 approaches require that every participating network interface (e.g., port) takes very accurate timestamps of selected packet ingress and/or egress, and manages precisely synchronized time. By taking timestamps at the edge of the physical layer for a network interface very close to the network medium, the time difference between when a packet is transmitted from a first network node to that packet being received at a second network node can be minimized.
To perform timestamp functions, the physical layer for the network interface would need to parse the packet using a standard IEEE 1588 packet format. Network nodes that utilize network layer 2 encryption such as MACSec encapsulate and protect the packet. As such, the physical layer would not be able to parse the encrypted packet correctly.